Colorectal cancer (CRC) is one of the most common cancers worldwide, with high mortality. Abnormally expressed microRNAs (miRNAs) are considered novel biomarkers in cancer diagnosis. The aim of this study was to investigate the diagnostic value of miR-92a-1 in patients with CRC. Serum samples were collected from 148 patients pathologically diagnosed with CRC and 68 gender- and age-matched healthy volunteers. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure serum miR-92a-1 level. Relationship between miR-92a-1 and clinicopathological features of CRC cases was analysed via chi-square test. Receiver operating characteristic (ROC) curve was plotted to estimate the diagnostic value of miR-92a-1 in CRC. Serum miR-92a-1 was significantly up-regulated in CRC patients compared with healthy individuals (P < .001). Moreover, miR-92a-1 expression was correlated with TNM stage (P = .02), histological stage (P = .003), lymph node metastasis (P = .003) and distant metastasis (P < .001). ROC analysis showed that the area under the ROC curve (AUC) was 0.914, suggesting high diagnostic accuracy of miR-92a-1 in ROC. The optimal cut-off value was 1.485, with a sensitivity of 81.8% and a specificity of 95.6%. MiR-92a-1 is increased in CRC patients and correlated with aggressive clinical characteristics. Serum miR-92a-1 may be a potential diagnostic biomarker for CRC.